Hydrophilic polypropylene fibers having antimicrobial activity

ABSTRACT

Polypropylene fibers and devices that include a fatty acid monoglyceride added to the polypropylene as a melt additive are described. A hydrophilic enhancer material can be advantageously added to the polypropylene as a melt additive to enhance the hydrophilicity of the fibers and devices. An antimicrobial enhancer material can be added to the fibers to enhance the antimicrobial activity.

This application is a division of U.S. patent application Ser. No.09/572,811, filed May 17, 2000, now U.S. Pat. No. 6,762,339, issuing onJul. 13, 2004 which claims the benefit of U.S. Provisional ApplicationNo. 60/135,381, filed May 21, 1999, and U.S. Provisional Application No.60/153,626, filed Sep. 13, 1999, the disclosures of which are herebyfully incorporated by reference herein.

FIELD OF THE INVENTION

In one aspect, this invention relates to hydrophilic polypropylenefibers which preferably have antimicrobial activity. In another aspectit relates to a multilayer absorbent device suitable as, e.g., a wounddressing, a medical drape, and the like.

SUMMARY OF THE INVENTION

Briefly, in one aspect, the invention provides a polypropylene fiberhaving incorporated therein a C₈ to C₁₆ fatty acid monoglyceride or amixture of glycerides containing at least 80 percent by weight of one ormore C₈ to C₁₆ fatty monoglycerides, and a hydrophilic enhancermaterial. The invention includes fibrous nonwoven, woven and knit websand batts made from such fibers.

In another aspect, the invention provides a hydrophilic polypropylenefiber comprising: (a) polypropylene; (b) an effective amount of at leastone C₈ to C₁₂ fatty acid monoglyceride added to the polypropylene as amelt additive to impart both hydrophilicity and antimicrobial activityto Gram-positive bacteria to the surface of the fiber; and (c) aneffective amount of an antimicrobial enhancer material such that thesurface of the fiber is antimicrobial to Gram-negative bacteria such asKlebsiella pneumoniae. Preferred antimicrobial enhancer materialsinclude organic acids and chelating agents, most preferably lactic acid.

In another aspect, the invention provides an absorbent devicecomprising: (a) an absorbent layer having upper and lower opposed, majorsurfaces and comprising fibers that are hydrophilic and, preferably,antimicrobial to Gram-positive bacteria; and (b) a liquid-impermeableand moisture vapor permeable backing sheet adhered to the upper surfaceof the absorbent layer. The fibers comprise polypropylene and aneffective amount of at least one C₈ to C₁₆ fatty acid monoglycerideadded to the polypropylene as a melt additive to render the surface ofthe fibers hydrophilic and, preferably, antimicrobial. In one preferredembodiment of this invention, the surface of the hydrophilic fibers aretreated with an effective amount of an antimicrobial enhancer material,such as lactic acid, such that the surface of the fibers in theabsorbent layer are antimicrobial to Gram-negative bacteria.

In one embodiment of the absorbent device, the absorbent layer andbacking sheet are substantially coextensive. When the absorbent deviceis used as a wound dressing, it can be positioned over the wound withthe absorbent layer positioned adjacent to the wound. The device is thenadhered to the skin around the wound, for example, by tape. In anotherembodiment of the absorbent device, the absorbent layer and the backingsheet are not substantially coextensive and the backing sheet extendsbeyond at least a portion of the outer perimeter of the absorbent layerto form an extended portion with an upper and lower surface. The lowersurface of the extended portion is adjacent to the absorbent layer andat least a portion of the lower surface carries an adhesive layer whichcan be used to adhere the absorbent device to the skin around the wound.Optionally, this embodiment can further comprise a release liner that issubstantially coextensive with the backing sheet and adhered to thebacking sheet by the adhesive layer. The release liner would be removedfrom the absorbent device prior to application to a wound.

A preferred embodiment of the absorbent device further comprises aliquid-permeable sheet that is substantially coextensive with, andadhered to, the lower surface of the absorbent layer. The liquidpermeable sheet permits passage of liquid, e.g., exudate, from the woundinto the absorbent layer, and preferably prevents adherence of theabsorbent layer to the wound. Optionally, the liquid permeable sheet canbe hydrophilic or antimicrobial, or both.

The invention also provides useful devices made from such fibers, suchas fabrics, webs, batts, and single and multi-layer nonwovenconstructions, which are employed in the manufacture of wound dressings,medical drapes, surgical gowns, surgical masks, disposable diapers,filter media, face masks, orthopedic cast padding/stockinettes,respirators, food packaging, dental floss, industrial wipes, textiles,and battery separators. In particular, the absorbent device of thepresent invention can advantageously be used as a wound dressing becauseit can (i) absorb a substantial quantity of wound exudate when thedressing is worn for an extended period of time or when the woundproduces a large quantity of exudate, and (ii) retard growth of bacteriain the absorbent layer, and, in some cases, in the wound. A furtheradvantage of the absorbent device is that the antimicrobial activity ofthe device reduces the sterilization load associated with the wounddressing when the device is sterilized prior to packaging such as, forexample, by exposure to ethylene oxide.

The invention further provides a method of preparing fibers that areboth hydrophilic and, preferably, antimicrobial to Gram-positive andGram-negative bacteria, the method comprising the steps of (i) preparinga hot melt mixture comprising melted polypropylene and an amount of atleast one C₈ to C₁₆ fatty acid monoglyceride that is effective to impartboth hydrophilicity and, preferably, antimicrobial activity toGram-positive bacteria to the surface of the fiber; and (ii) shaping themixture into the desired shape, for example forming the fibers byextrusion through a die. When it is desired that the fibers also beantimicrobial to Gram-negative bacteria, the method further comprisesthe step of contacting the shaped mixture with a liquid compositioncomprising at least one antimicrobial enhancer material, thereby coolingand at least partially solidifying the shaped mixture and, when present,evaporating sufficient solvent or carrier liquid from the liquidcomposition to yield an essentially dry coating of the antimicrobialenhancer material on the surface of the shaped mixture that is ofsufficient concentration and uniformity such that the extruded surfaceis antimicrobial to Gram-negative bacteria. When both hydrophilicity andantimicrobial activity are desired, preferably the monoglyceride is aC₈-C₁₂ fatty acid monoglyceride, such as, for example, glycerolmonolaurate. Some embodiments of the aforementioned fibers furtherincorporate an effective amount of a hydrophilic enhancer material addedto the polypropylene as a melt additive to enhance the hydrophilicity ofthe fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be made tothe following description of exemplary embodiments taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an absorbent deviceaccording to the invention.

FIG. 2 is a schematic cross-sectional view of another absorbent deviceaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, “hydrophilic”, “hydrophilicity” or similar terminologyis used to describe substrates (e.g., fibers, woven or nonwoven fabrics,webs, knits or fiber batts etc.) that can be wet by water, by aqueoussolutions of acids and bases (e.g., aqueous potassium hydroxide) and bypolar liquids (e.g. sulfuric acid and ethylene glycol).

As used herein, “antimicrobial” or “antimicrobial activity” means that amaterial has sufficient antimicrobial activity as measured by AmericanAssociation of Textile and Color Chemists (AATCC) Test Method 100-1993(AATCC Technical Manual, 1997, pp. 143 to 144), to reduce an initialbacterial load by at least 90% over a 24-hour exposure period at 23-24°C.

The terms “fiber” and “fibrous” as used herein refer to particulatematter, generally comprising thermoplastic resin, wherein the length todiameter ratio of the particulate matter is greater than or equal toabout 10. Fiber diameters may range from about 0.5 micron up to at least1,000 microns and each fiber may have a variety of cross-sectionalgeometries, may be solid or hollow, and may be colored by, e.g.,incorporating dye or pigment into the polymer melt prior to extrusion.

The term “nonwoven web” or “nonwoven fabric” means a web or fabrichaving a structure of individual fibers which are interlaid, but not ina regular manner, such as knitting and weaving. Nonwoven fabrics or webshave been formed from many processes such as, for example, melt blowingprocesses, spunbonding processes, and bonded carded web processes.

The term “spunbonded fibers” refers to small diameter fibers which areformed or “spun” by extruding molten thermoplastic material in the formof filaments from a plurality of fine, usually circular, capillaries ofa spinneret, and then rapidly reducing the diameter of the extrudedfilaments, for example, by the methods described in U.S. Pat. No.4,340,563 (Appel et al.) and U.S. Pat. No. 3,692,618 (Dorschner et al.).The “spun” fabric is then passed between the rolls of a heated calenderto bond the fibers together. Various patterns can be imparted to thefabric by the calender rolls, but the principle purpose of bonding is toincrease the integrity of the fabric. The bond area in thermal bondingis usually about 15%, but may vary widely depending on the desired webproperties. Bonding may also be accomplished by needling,hydroentanglement, or other methods known in the art.

The term “melt blown fibers” refers to fibers which are typically formedby extruding the molten thermoplastic material through a plurality offine, usually circular, die capillaries as molten threads or filamentsinto a high velocity, usually heated gas (e.g., air) stream whichattenuates the filaments of molten thermoplastic material to reducetheir diameter. Thereafter, the melt-blown fibers are carried by thehigh velocity gas stream and are deposited on a collecting surface toform a web of randomly disbursed melt-blown fibers. Any of the nonwovenwebs may be made from a single type of fiber or two or more fibers whichdiffer in composition and/or thickness. Alternatively, sheath-corefibers can be extruded containing different polymer compositions in eachlayer, or containing the same polymer composition in each layer butemploying the more hydrophilicity-imparting component in the outersheath layer.

The polymers useful in preparation of the hydrophilic fibers of thepresent invention are polypropylenes, including isotactic polypropylene,syndiotactic polypropylene, and mixtures of isotactic, atactic and/orsyndiotactic polypropylene.

The monoglycerides useful in the invention are derived from glycerol andmedium to long chain length (i.e., C₈ to C₁₆) fatty acids such ascaprylic, capric, and lauric acids. Most preferably, the monoglyceridesare derived from C₁₀ to C₁₂ fatty acids and are food grade and GenerallyRegarded as Safe (“GRAS”) materials. Examples of preferredmonoglycerides include glycerol monolaurate, glycerol monocaprate, andglycerol monocaprylate. Because the monoglycerides useful in theinvention are typically available in the form of mixtures of unreactedglycerol, monoglycerides, diglycerides and triglycerides, it ispreferred to use mixtures that contain a high concentration (e.g.,greater than about 80%, preferably greater than about 85 wt. %, morepreferably greater than about 90 wt. %, and most preferably greater thanabout 92 wt. %) of the monoglyceride. A convenient way to determinewhether one of the aforementioned mixtures, or even a particularmonoglyceride, will work in the invention is to calculate thehydrophilic-lipophilic balance (“HLB value”) for the mixture. Typically,the HLB value of one of the aforementioned mixtures decreases withincreasing fatty acid chain lengths, and also decreases as thediglyceride and triglyceride content in the mixture increases. Usefulmaterials (including pure monoglycerides) typically have HLB values ofabout 4.5 to about 9, more preferably from about 5.3 to about 8.5.Examples of particularly useful commercially available materials includethose available from Med-Chem Laboratories, East Lansing, Mich., underthe tradename LAURICIDIN™, Riken Vitamin Ltd., Tokyo, Japan under thetradename POEM™, and Henkel Corp. of Germany under the tradename“MONOMULS™ 90 L-12”.

Generally, it is difficult to impart hydrophilicity to polypropylenefibers using surfactants. Conventional surfactants typically must beadded to polypropylene at higher concentrations than are used inpolyethylene, and it is difficult to find effective surfactants that canbe used in polypropylene at low concentrations. The impact of the use ofhigh concentrations of conventional surfactants is increased cost, insome instances impairment of the physical properties of the extrudedfiber, or impairment of processability of the extrudable polyolefinmixture (e.g., screw slippage, see T. Klun, et al., “Hydrophilic MeltAdditives, Synergistic Fluorochemical/Hydrocarbon Surfactant Mixtures,”Proceedings of INDA-TEC '97, Cambridge, Mass., Sep. 8-10, 1997). It isquite surprising that the monoglycerides used in this invention canimpart good hydrophilicity to polypropylene at concentrations of onlyabout 3 weight percent or less, when typically at least about 5 weightpercent of other hydrocarbon surfactants is required to impartacceptable hydrophilicity to polypropylene.

The fibers of this invention can be made by blending or otherwiseuniformly mixing at least one C₈ to C₁₆ fatty acid monoglyceride and thesolid polypropylene, for example, by intimately mixing the monoglyceridewith pelletized or powdered polymer, and melt extruding the mixture intoa fibrous web using any of the commonly known processes for producingnonwoven webs, such as by using the spunbonding techniques ormelt-blowing techniques, or combinations of the two, described above.The monoglyceride can be mixed per se with the polypropylene, or it canbe mixed with the polymer in the form of a “masterbatch” (concentrate)of the monoglyceride in the polymer. Masterbatches can typically containfrom about 10% to as much as about 25% by weight of the monoglyceride.Also, an organic solution of the monoglyceride can be mixed with thepowdered or pelletized polymer, the mixture dried to remove solvent,then melted and extruded into the desired shape. Alternatively, the neatform of monoglyceride can be injected into a molten polymer stream toform a blend just prior to extrusion into the desired shape. Afterextrusion, an annealing step may be carried out to enhancehydrophilicity. Preferably, the article is annealed at a temperature andfor a time sufficient to increase the amount of monoglyceride at thesurface of the article. Effective time and temperature will bear aninverse relationship to one another and a wide variety of conditionswill be suitable. Using polypropylene, for example, the annealingprocess can be conducted below the melt temperature at about 60° toabout 80° C. for a period of about 30 seconds to about 5 minutes ormore. In some cases, the presence of moisture during annealing canimprove the effectiveness of the monoglyceride. The annealing of afibrous web can be carried out, for example, in combination with otherprocessing steps for the web (e.g., during the warm cycle of an ethyleneoxide sterilization cycle). Hydrophilicity may also be enhanced bycontacting the shaped article with heated surfaces, such as hot rolls atabout 60° C. to 100° C. for about 10-60 seconds.

Melt-blown hydrophilic fibers useful in the present invention can beprepared as described in U.S. Pat. No. 3,849,241 (Butin et al.) and U.S.Pat. No. 5,064,578 (Insley et al.), or from microfiber webs containingparticulate matter such as those disclosed, for example, in U.S. Pat.No. 3,971,373 (Braun), U.S. Pat. No. 4,100,324 (Anderson), and U.S. Pat.No. 4,429,001 (Kolpin et al.). Multilayer constructions of nonwovenfabrics enjoy wide industrial and commercial utility and include suchuses as fabrics for medical gowns and drapes. The nature of theconstituent layers of such multilayer constructions can be variedaccording to the desired end use characteristics, and can comprise twoor more layers of melt-blown and spun-bond webs in many usefulcombinations, such as those described in U.S. Pat. No. 5,145,727 (Pottset al.) and U.S. Pat. No. 5,149,576 (Potts et al.). In particular, aprocess similar to that described in Wente, Superfine ThermoplasticFibers, 48 INDUS. ENG'G CHEM. 1342(1956), or in Wente et al.,MANUFACTURE OF SUPERFINE ORGANIC FIBERS, (Naval Research LaboratoriesReport No. 4364, 1954), can be used for the preparation of the nonwovenwebs of this invention. However, because of the potential for thermalinstability of the glycerol monoesters employed in the invention as meltadditives, it is preferable to incorporate the monoester into thepolymer melt just before or just after the die, such as is generallydescribed in U.S. Pat. No. 4,933,229 (Insley et al.) and U.S. Pat. No.5,064,578 (Insley et al.).

Preferred hydrophilic enhancer materials include polybutylene,polybutylene copolymers, ethylene/octene copolymers, atacticpolypropylene, and certain sorbitan monoesters. Polybutylene and itscopolymers, such as, for example, polybutylene 0200, polybutylene 0400,polybutylene 0800, polybutylene DP 8310, and polybutylene DP 8340 (allavailable from Shell Chemical Co.), ethylene/octene copolymers, such as,for example, ENGAGE™ 8401 and 8402 (available from DuPont DowElastomer), ethylene/butylene and butylene/ethylene copolymers, forexample, EXACT™ 4023 (available from Exxon) and MONTELL™ dp-8340(AVAILABLE FROM Montell), and atactic poly(alpha)olefins, such asAPAO-2180-E8 atactic polypropylene, a high molecular weight homopolymerof polypropylene, available from Rexene Co., may be incorporated as anadditional polymer melt additive to enhance the hydrophilic propertiesof the extrudate. Effective concentrations of the polybutylenehomopolymer and copolymers, determined by measuring the amountincorporated as a melt additive prior to fiber formation, range fromabout 2 to about 25% by weight, and preferably from about 5% to about15% by weight. The enhancement effect is seen at polybutylene levels upto about 25% by weight, and at monoglyceride concentrations as low as1.0% by weight, based on the weight of the composition prior to fiberformation.

C₈ to C₁₆, preferably C₁₂ to C₁₆ sorbitan monoesters such as SPAN™ 20(sorbitan monolaurate) or SPAN™ 40 (sorbitan monopalmitate) for exampleEXACT™ 4023 (available from Exxon) and MONTELL™ DP-8340 (available fromMontell), in combination with the monoglyceride, with or withoutpolybutylene, can further enhance the hydrophilic properties of theextrudate. These monoesters both enhance the hydrophilicity of the weband allow the web to maintain its hydrophilicity after aging at ambientconditions. When these hydrophilic enhancer materials are used, they mayreplace from about 10% to about 50% of the monoglyceride, preferablyfrom about 30% to about 50%.

In addition to the hydrophilic fibers of the present invention, thenonwoven webs or fabrics and fiber batts can further include commonlyused hydrophilic fillers such as, for example, wood pulp, cellulose,cotton, rayon, recycled cellulose, and shredded cellulose sponge, aswell as adhesive binders and antistats.

Any of a wide variety of constructions, especially multilayerconstructions such as spunbond/melt-blown/spunbond (“SMS”)constructions, may be made from the above-described fibers and fabrics,and such constructions will find utility in applications requiringhydrophilicity. Such constructions include aqueous media absorbentdevices such as diapers, feminine care products, and adult incontinenceproducts, which utilize the fiber and fabrics as at least a portion oftheir fluid-absorbing “core” element. “Absorbent device” as used hereinrefers to a consumer product that is capable of absorbing significantquantities of water and other aqueous fluids (i.e., liquids) such asbody fluids. Examples of aqueous media absorbent devices include wounddressings, disposable diapers, sanitary napkins, tampons, incontinencepads, disposable training pants, paper towels, geofabrics, facialtissues, medical drapes and masks, medical gowns, and the like. Thefabrics of the present invention are particularly suitable for use indevices like sanitary napkins, diapers, and incontinence pads.

Aqueous media absorbent devices frequently will comprise a substantiallyaqueous media impervious and moisture vapor-permeable backing sheet, anaqueous media permeable top sheet, and an aqueous media absorbent corecomprising at least one aqueous media absorbent layer positioned betweensaid backing sheet and said top sheet. The aqueous media imperviousbacking sheets may comprise any suitable material, such as polyethylene,polypropylene and polyurethane, preferably having a thickness of atleast about 0.020 mm, which will help retain fluid within the absorbentarticle. The aqueous media impervious backing sheet may also comprise afabric treated with a water repellent material. The aqueous mediapermeable top sheets can comprise material, such as polyester,polyolefin, rayon, and the like, that is substantially porous andpermits aqueous media to readily pass therethrough into the underlyingabsorbent core. Suitable materials for both the top sheets and thebacking sheets are well known in the art.

More detailed descriptions of sanitary napkins and suitable materialsfor use therein may be found in U.S. Pat. No. 3,871,378 (Duncan et al.),U.S. Pat. No. 4,324,246 (Smith et al.), and U.S. Pat. No. 4,589,876 (VanTillberg).

Disposable diapers comprising the hydrophilic fabrics of the inventionmay be made by using conventional diaper making techniques, replacing orsupplementing the wood pulp fiber core typically employed with thefabrics comprising hydrophilic fibers of the present invention. Thehydrophilic fibers of the invention may also be used to inputhydrophilicity to the top sheet of such an article where hydrophilicityis desired. The hydrophilic fabrics of this invention may thus be usedin diapers in single layer or in multiple layer core configurations.Articles in the form of disposable diapers are described by U.S. Pat.No. 3,592,194 (Duncan et al.), U.S. Pat. No. 3,489,148 (Duncan et al.),and U.S. Pat. No. 3,860,003 (Buell).

Preferably, a liquid composition comprising at least one antimicrobialenhancer material and optionally a liquid vehicle is applied by, e.g.,dipping, spraying, printing, padding or by brush or sponge, to a portionof or the entire exterior surface of the shaped article, namely, fibers,woven and nonwoven fabrics or webs, and batts. The liquid vehicle isthen removed, typically by drying, from the liquid composition toprovide an essentially dry coating of the antimicrobial enhancermaterial containing at least about 50 weight percent enhancer material,preferably at least about 75 weight percent enhancer material, and morepreferably at least about 95 wt. % enhancer material on the surface ofthe article. The antimicrobial enhancer, when combined in sufficientconcentration and uniformity with a fiber prepared with themonoglyceride melt additive, enhances either the antimicrobial activityof the article surface or the spectrum of antimicrobial activity, thatis, the article surface has antimicrobial activity to both Gram-positiveand Gram-negative bacteria. Preferred antimicrobial enhancer materialsare organic acids and chelating agents. Examples of suitableantimicrobial enhancer materials include: lactic acid, tartaric acid,adipic acid, succinic acid, citric acid, ascorbic acid, malic acid,mandelic acid, acetic acid, sorbic acid, benzoic acid, salicylic acid,sodium acid pyrophosphate, acidic sodium hexametaphosphate (such asSPORIX™ acidic sodium hexametaphosphate and ethylenediaminetetraaceticacid or EDTA) and salts thereof. Preferred materials are both food gradeand GRAS materials, and a particularly preferred antimicrobial enhancermaterial is lactic acid. Typically, the liquid composition is preparedby dissolving, dispersing or emulsifying the antimicrobial enhancermaterial in a liquid vehicle such as water and/or a lower alcohol, suchas ethanol, to provide a liquid composition comprising from about 1.0 toabout 50 wt. % enhancer material based on total weight of the liquidcomposition. A preferred method for applying the liquid composition toextruded fibers is to spray the hot fibers as they exit the extrusiondie. Typical spray rates of about 3 kg/hr to about 25 kg/hr of anaqueous lactic acid solution are suitable for fiber extrusion rates ofabout 90 to about 100 kg/hr. Undiluted liquid lactic acid or anydilution up to a 1 part lactic acid per 3 parts water are preferred.Solvent removal, if necessary, can be accomplished by drying the coatedfibers in an oven.

Turning now to the drawings, in FIG. 1 there is shown an absorbentdevice 10. The device has an absorbent layer 11 which is substantiallyconformable and is comprised of one or more layers of nonwoven or wovenfabrics, webs or fiber batts. The layers are comprised of fibers thatare hydrophilic and, preferably, also antimicrobial to Gram-positivebacteria, and even more preferably, to Gram-negative bacteria as well.Where more than one layer of fabric, web or fiber batt is employed tomake the absorbent layer, the layers may be bonded together by meltbonding (e.g., pattern bonding or radio frequency bonding) or adhesivesto form a single, unitary layer. Suitable adhesives include hot meltspray adhesives such as HL-1685-X or HL-1710-X, both of which arecommercially available from H.B. Fuller Co., St. Paul, Minn. The hotmelt adhesive can be applied using spiral spray adhesive systems such asthose commercially available from Nordson Corporation, Duluth, Ga.Typical adhesive application rates using such systems are about 6 to 10grams/m². In addition, the fibers may be combined with other additivescommonly used to prepare absorbent fabrics or batts, such as wood pulp,cellulose, cotton, rayon, recycled cellulose, shredded cellulose spongeand binders. Typically, the thickness of the absorbent layer is fromabout 0.5 to about 10 mm.

The absorbent layer 11 has an upper surface 12 and a lower surface 13.Adhered to the upper surface 12 is a substantially conformable andsubstantially coextensive, liquid-impermeable backing sheet 14. Thebacking sheet 14 can be essentially continuous, or it can bemicroporous, and preferably it is moisture vapor-permeable so as toprevent an unacceptable buildup of moisture within the absorbent devicewhen the absorbent layer 11 is saturated, for example, with woundexudate. The backing sheet 14 is typically about 0.02 to about 0.12 mmthick, and can be selected from a variety of commonly known polymericfilms, such as polyurethane and polypropylene films. A microporous filmpreferred for use as a backing sheet can be prepared according to themethod of U.S. Pat. No. 4,726,989 (Mrozinski), and particularly theprocedure described in Examples 1-8 of that patent, without the solventextraction of the oil. The backing sheet 14 can be adhered to theabsorbent layer 11 by melt bonding (e.g., pattern bonding or radiofrequency bonding), or by a continuous or discontinuous adhesive layer(not shown) comprising, for example, one of the non-cytotoxic adhesivesknown in the art such as those described above.

Optionally, a substantially conformable liquid-permeable sheet 15 isadhered to the lower surface 13 of the absorbent layer 11. By “adhered”is meant that sheet 15 abuts and extends along the lower surface 13 andcan be, but need not be, attached thereto by adhesive means. Theliquid-permeable sheet 15 is preferably substantially coextensive withthe absorbent layer 11 and adhered to it either by melt bonding or by anadhesive as described hereinabove (e.g., a hot melt spray adhesive).Typically, the liquid-permeable sheet is about 0.05 mm to about 0.075 mmthick, and is substantially porous to permit free flow of liquid. Aparticularly preferred liquid-permeable sheet is the non-stick nettingcommercially available from Applied Extrusion Technologies, Middletown,Del. as Delnet CKX215 P-S or Delnet P530-S.

Another embodiment of the absorbent device is depicted in FIG. 2. Shownin FIG. 2 is an absorbent device 20. The device 20 has an absorbentlayer 21 with an upper surface 22 and lower surface 23. Adhered to theupper surface 22 of the absorbent layer 21 is a substantiallyconformable backing sheet 24. However, in this embodiment, the backingsheet 24 is not coextensive with the absorbent layer 21. Instead, thebacking sheet 24 extends beyond the outer perimeter of the absorbentlayer 21, preferably uniformly, to provide an extended portion 25 with alower surface 26. The lower surface of the extended portion 25 carriesan adhesive layer 27 that can be used to adhere the absorbent device tothe target, such as the skin around a wound. The adhesive 26, preferablya pressure sensitive adhesive, may be in the extended portion 25 or maybe covering the entire surface 22. Preferred adhesives include adhesiveshaving good adhesion to skin and resistance to moisture. Examples ofsuch adhesives are those described in U.S. Pat. No. 5,648,166 (Dunshee).

Optionally, the device also includes a substantially conformable,liquid-permeable sheet 29 adhered to the lower surface 23 of theabsorbent layer 21. Most preferably, the liquid permeable sheet 29 iscoextensive with the absorbent layer 21. The device also optionallyincludes a release liner 30 that is substantially coextensive with andadhered to the backing sheet 24 by the adhesive layer 27. Prior toapplication of the absorbent device 20 to the target, the release liner30 is removed from the absorbent device. Examples of suitable adhesivesfor adhesive layer 27 include any of the non-cytotoxic adhesivesdescribed hereinabove. Release liner 30 can be any polymeric film, paperor foil known in the art to be useful as a release liner. Examples ofuseful release liners include 50 g/m² basis weight SC 501FM40 whiteSopal Flexible Packaging available from Day Cedex, France. The backingsheet 24, absorbent layer 21, and liquid permeable sheet 29 can be thesame as those elements used in the absorbent device depicted in FIG. 1.However, moisture vapor-permeable adhesive coated films like thosedescribed in U.S. Pat. No. 4,726,989 can also be used as the backingsheet 24.

The invention may also find particular utility as an antimicrobial facemask, e.g., a surgical mask, or as an antimicrobial medical drape orgown, e.g., a surgical drape. Face masks are used as barriers betweenthe wearer and the environment, and are well described in the art, e.g.,in U.S. Pat. No. Re. 28,102 (Mayhew). Through their filtrationefficiency, face masks can remove particulates (organic, inorganic, ormicrobiological) from the incoming or out going breath. Face masks aregenerally not antimicrobially active even though they are commonly usedin a health care setting as a method of minimizing pathogen transmissionrisk. The invention includes a face mask with antimicrobial activity,that is a mask capable of killing microorganisms that come into contactwith it. This activity extends to antimicrobial kill of such commonorganisms like bacteria, fungi, the influenza A virus, and therhinovirus, the cause of the common cold. Surgical drapes may beconstructed from single layers of a fibrous web material or includemulti-layered laminates that include one or more film layers, e.g., asdescribed in U.S. Pat. No. 3,809,077 (Hansen) and U.S. Pat. No.4,522,203 (Mays). Surgical drapes require sterilization prior to use andsince the drapes generally do not have inherent antimicrobial activity,any microbial contamination can remain on the surface of these drapes.

The invention includes surgical drapes that can be self-sterilizingthrough the application of an antimicrobial coating to the surface ofthe surgical drape. Active surfaces like the self-sterilizing surgicaldrapes of this invention can provide long term antimicrobial kill ofmicroorganisms coming in contact with the drape surface. The followingexamples are offered to aid in understanding of the present inventionand are not to be construed as limiting the scope thereof. Unlessotherwise indicated, all parts and percentages are by weight.

GLOSSARY Hydrocarbon Surfactants

GML: glycerol monolaurate, available from Med-Chem Laboratories, EastLansing, Mich. under the tradename “LAURICIDIN™.”

GM-C8: glycerol monocaprylate, available as POEM™ M-100 from RikenVitamin LTD, Tokyo, Japan.

GM-C10: glycerol monocaprate, available as POEM™ M-200 from RikenVitamin LTD., Tokyo, Japan.

GM-C12: glycerol monolaurate, prepared as follows: A 250-mL three-neckedflask equipped with thermometer, addition funnel and nitrogen inletadapter was charged with 100.16 g (0.5 mol) of lauric acid (availablefrom. Sigma-Aldrich Co., Milwaukee, Wis.) and 0.7 g (0.5% with respectto the total weight of reactants) of benzyl triethylammonium chloride(the catalyst, available from Sigma-Aldrich Co.). The reaction mixturewas heated to an internal temperature of 114° C. using a silicone oilbath at 119° C. Next, 38.89 g (0.525 mol) of glycidol (available fromSigma-Aldrich Co.) was added at a constant rate over 22 minutes with theinternal temperature rising to a maximum of 130° C. at 20 minutes.Within 1.5 hours, the temperature of the reaction had fallen to 113° C.At 6.5 hours, the reaction was stopped and 134.19 g of product wasisolated. The product was analyzed by ¹H and ¹³CNMR spectroscopy, andthe ratios of products were established by assignment and quantitativeintegration of the glycerol carbons.

GM-C14: glycerol monomyristate, prepared as follows: Using a proceduresimilar to that described for the preparation of GM-C12, 114.19 g (0.5mol) of myristic acid (available from Sigma-Aldrich Co.), 38.9 g (0.525mol) of glycidol, and 0.77 g of benzyl triethylammonium chloride werereacted for 18 hours to provide 143.5 g of product.

GM-C16: glycerol monopalmitate, prepared as follows: Using a proceduresimilar to that described for the preparation of GM-C12, 89.75 (0.35mol) of palmitic acid (available from Sigma-Aldrich Co.), 27.22 g(0.3675 mol) of glycidol, and 0.58 g of benzyl triethylammonium chloridewere reacted for 6 hours to provide 114.4 g of product.

GM-C18: glycerol monostearate, prepared as follows: Using a proceduresimilar to that described for the preparation of GM-C12, 142.24 (0.5mol) of stearic acid (available from Sigma-Aldrich Co.), 36.67 (0.495 gmol) of glycidol, and 0.895 g of benzyl triethylammonium chloride werereacted for 18.5 hours to provide approximately 170 g of product.

GM-C18D: glycerol monostearate, prepared as follows: An aliquot of about60 g of GM-C18 was distilled using a single plate distillation at a headtemperature of 240° C. at 0.5 torr to provide about 25 g of distillate.

HS-1: glycerol monococoate, available as LUMULSE™ GML from LambertTechnologies, Skokie, Ill.

HS-2: glycerol monooleate, available as LUMULSE™ GMO from LambertTechnologies.

HS-3: glycerol monostearate, available as EMEREST™ 2400 from HenkelCorp., Organic Products Division, Charlotte, N.C.

HS-4: glycerol monoisostearate, prepared as follows: A 1-L 3-neckedround bottom flask equipped with heating mantle, stirrer, thermometer,and Dean-Stark apparatus was charged with 284.48 g (1 mol) of isostearicacid (available as EMEREST™ 873 from Henkel Corp.), 92.09 g (1 mol) ofglycerol, 2.26 g of p-toluenesulfonic acid (available from Sigma-AldrichChemical Co., Milwaukee, Wis.), and 131.8 g of toluene. The resultingmixture was stirred and heated overnight, using Dean-Stark conditions,was allowed to cool to 80° C., was neutralized with 1.75 g oftriethanolamine, and was filtered through a Buchner funnel containing apad of CELITE™ filtering medium (available from Aldrich Chemical Co.,Milwaukee, Wis.). The filtrate was concentrated by removing solvent at150° C. and 40 torr pressure to provide an amber liquid product.

HS-5: PEG 600 dioleate, available as MAPEG™ 600DO from BASF Corp.,Specialty Chemicals; Mount Olive, N.J.

HS-6: PEG 400 monotallate, available as MAPEG™ 400MOT from BASF Corp.,Specialty Chemicals.

HS-7: ethoxylated (9.5) octylphenol, available as TRITON™ X-100 fromUnion Carbide Corp, Danbury, Conn.

HS-8: polyoxyalkylene (10) oleyl ether, available as BRIJ™ 97 from ICISurfactants, Wilmington, Del.

HS-9: a phenoxyaryl alkyl ethoxylate, available as EMULVIN™ from BayerCorp., Pittsburgh, Pa.

SPAN™ 20: sorbitan monolaurate, 100% active, having an HLB of 8.6,available from Uniquma (ICI Surfactants), Wilmington, Del.

SPAN™ 40: sorbitan monopalmitate, 100% active, having an HLB of 6.7,available from Uniquma (ICI Surfactants), Wilmington, Del.

ARLACEL™ 60: sorbitan monostearate, 100% active, having an HLB of 4.3,available from Uniqema (ICI Surfactants).

ARLACEL™ 83: sorbitan sequioleate (1½ mole adduct), 100% active, havingan HLB of 3.7, available from Uniqema (ICI Surfactants).

Fluorochemical Surfactants

FS-1: a hydrophilic fluorochemical polymer melt additive for nonwovens,available as 3M™ FC-1802 Protective Chemical from 3M Company, St. Paul,Minn.

FS-2: MeFOSA/TRITON™ X-100 adduct, made by the condensation reaction ofTRITON™ X-100 chloride with MeFOSA amide (C₈F₁₇SO₂NH₂) as follows:

First, TRITON™ X-100 chloride was made according to the followingprocedure: To a 3-necked round bottom flask equipped with overheadstirrer, thermometer, reflux condenser and two attached gas washingbottles (the second bottle containing a 10% aqueous solution of sodiumhydroxide) was charged 646 g (1.0 mol) of TRITON™ X-100 and 12.9 g ofCELITE™ filtering medium. The resulting mixture was heated to 60° C.,then 142.76 g (1.2 mol) of thionyl chloride was added via an additionfunnel over a period of about 22 minutes, raising the reaction mixturetemperature to 75° C. Then nitrogen was bubbled through the reactionmixture for 4 hours, during which time the mixture temperature variedfrom 68-71° C. The reflux condenser and gas washing bottles werereplaced by a still head, and the reaction mixture was stirred while avacuum of about 50 torr absolute pressure was applied. After thereaction was shown to be complete by ¹³C and ¹H NMR analysis, thereaction mixture was filtered hot through a C-porosity fritted glassBuchner funnel to yield a light yellow product, TRITON™ X-100 chloride.

The TRITON™ X-100 chloride was then reacted with MeFOSA using thefollowing procedure. To a 3-necked round bottom flask equipped withoverhead stirrer, reflux condenser and nitrogen inlet adapter wascharged 125 g (0.244 eq) of MeFOSA (which can be made as described byBrice et al. in U.S. Pat. No. 2,732,398), 177.80 g of TRITON™ X-100chloride, 30.18 (0.2794 eq) of sodium carbonate and 2.46 g (0.0149 eq)of potassium iodide. The resulting reaction mixture was heated to 120°C. for 8 hours, at which time the MeFOSA had disappeared according to gcanalysis. After cooling to 95° C., the reaction mixture was washed with157 g of 10% aqueous sulfuric acid, followed by 157 g of deionizedwater. The washed reaction mixture was concentrated by evaporation on arotary evaporator at 70° C. and 50 torr absolute pressure to give 252.6g of a brown liquid (92.2% yield). The structure of the desired productwas confirmed by ¹³C and ¹H NMR spectroscopy.

Silicone Surfactant

SS-1: NUWET™ 500 silicon ethoxylate, available from Osi Specialties,Inc., Danbury, Conn.

Thermoplastic Polymers

PP 3505: ESCORENE™ PP3505 polypropylene, having a 400 melt index flowrate, available from Exxon Chemical Co., Baytown, Tex.

PP 3746: ESCORENE™ PP3746 polypropylene, having a 1400 melt index flowrate, available from Exxon Chemical Co.

EOD 96-36: FINA™ EOD-96-36 polypropylene, having a 750 melt flow index,available from Fina Corp., La Porte, Tex.

3960X: FINA™ 3960X polypropylene, having a 350 melt flow index,available from Fina Corp., LaPorte, Tex.

3155: EXXON™ 3155 polypropylene, having a 35 melt flow index, availablefrom Exxon Chemical co.

4023: EXACT™ 4023 ethylene/butylene copolymer, containing a majority byweight of ethylene, available from Exxon Chemical Co.

PB 0400: MONTELL™ 0400 1-butylene homopolymer, having a 20 nominal meltindex, available from Montell, Houston, Tex.

DP-8910: MONTELL™ DP-8910 polybutylene, containing peroxide, availablefrom Montell.

DP-8340: MONTELL™ DP-8340 1-butylene/ethylene copolymer, having a meltflow index of 35, available from Montell.

8401: ENGAGE™ 8401, an ethylene/octene copolymer containing 19% octeneby weight, having a melt flow index of 30, available from DuPont DowElastomer.

8402: ENGAGE™ 8402, an ethylene/octene copolymer containing 13.5% octeneby weight, having a melt flow index of 30, available from DuPont DowElastomer.

Antimicrobial Enhancer Material

LA: Lactic acid, USP, commercially available from J.T. Baker,Phillipsburg, N.J.

Analyses and Test Methods

Analyses and Calculated Hydrophilic-Lipophilic Balance (HLB) Values ofGlycerol Monoesters

Table 1 provides the weight percent of monoglycerides, diglycerides,triglycerides, and glycerol present in a number of the materialsdescribed in the glossary. The mole percent values of the materials wereestablished by assignment and quantitative integration of the glycerolcarbons in the ¹³C NMR spectrum of each material, and the mole percentvalues were translated into weight percent values. The amounts of 1- and2-substituted monoglycerides as well as the amounts of the 1,2- and1,3-diglycerides were combined to determine, respectively, the weightpercent fractions of monoglycerides, and diglycerides presented in thetable.

Also presented in Table 1 are calculated HLB values for each material.The HLB values for each monoglyceride, diglyceride and triglyceridepresent in the materials were calculated using a group contributionmethod. The HLB value for glycerol was also calculated. In this method,HLB values are derived using the relation:

HLB=7+Σ (hydrophilic group number)−Σ (hydrophobic group number). Thegroup numbers for the particular monoglycerides, diglycerides andtriglycerides as well as glycerol are given in Tables I-IV on page 374of the reference: J. T. Davies and E. K. Rideal, Interfacial Phenomena,Second Edition, Academic Press, London, 1963.

The HLB value for each material was then calculated using the weightfraction of glycerol and each monoglyceride, diglyceride andtriglyceride component in the material using the following equation:

HLB  mixture = (wt.  fraction  monoglyceride) × (HLB  monoglyceride) + (wt.  fraction  diglyceride) × (HLB  diglyceride) + (wt.  fraction  triglyceride) × (HLB  triglyceride) + (wt.  fraction  glycerol) × (HLB  glycerol)

TABLE 1 Monoglyceride # Carbons in Calculated Glossary Component ofMonoglyceride Monoglycerides Diglycerides Triglycerides Glycerol Weight% HLB Designation Surfactant Fatty Acid (wt. %) (wt. %) (wt. %) (wt. %)Total Mixture GM-C8 Glycerol 8 88.8 7.4 0.0 3.8 100 8.3 monocaprylateGM-C10 Glycerol 10 89.1 6.5 0.0 4.4 100 7.4 monocaprate GML Glycerol 1294.0 5.7 0.0 0.3 100 6.3 monolaurate GM-C12 Glycerol 12 90.5 8.3 0.0 1.1100 6.2 monolaurate HS-1 Glycerol 12 44.5 38.0 .3 8.3 100 4.3monococoate GM-C14 Glycerol 14 88.4 6.8 1.2 3.6 100 5.3 monomyristateGM-C16 Glycerol 16 93.8 4.3 0.0 1.8 100 4.5 monopalmitate GM-C18Glycerol 18 87.7 6.4 2.7 3.2 100 3.0 monostearate GM-C18D Glycerol 1892.3 4.5 0.0 3.2 100 3.6 monostearate HS-3 Glycerol 18 56.5 35.1 2.0 6.4100 1.2 monostearate HS-2 Glycerol 18 50.9 41.1 4.2 3.9 100 0.2monooleateEffective Fiber Diameter (EFD) Measurement

EFD measurements were made according to the procedure outlined inDavies, C. N., “The Separation of Airborne Dust and Particles”,Institute of Mechanical Engineers, London, Proceedings 1B, 1952.

Melt-Blown Extrusion Procedure A

This melt-blown extrusion procedure was the same as described in U.S.Pat. No. 5,300,357 (Gardiner), at column 10. A Brabender 42 mm conicaltwin screw extruder was used, with a maximum extrusion temperature of255° C. and distance to the collector of 12 inches (30 cm).Monoglyceride and polypropylene mixtures were prepared by blending themonoglyceride and polypropylene in a paperboard container using a mixerhead affixed to a hand drill for about one minute until a visuallyhomogeneous mixture was obtained. The process condition for each mixturewas the same, including the melt blowing die construction used to blowthe microfiber web. The basis weight of the resulting webs, unlessotherwise stated, was 50±5 g/m² (GSM), and the targeted diameter of themicrofibers was 7 to 12 micrometers. The width of the web was about 12inches (30.5 cm). Unless otherwise stated, the extrusion temperature was255° C., the primary air temperature was 258° C., the pressure was 124KPa (18 psi), with a 0.076 cm air gap width, and the polymer throughputrate was about 180 g/hr/cm.

The measured average effective fiber diameter for each type of polymerused in the Examples was as follows:

PP 3505: 7.5 to 12.0 microns EOD 96-36 polypropylene: 7.4 to 11.4micronsMelt-Blown Extrusion Procedure B

This Procedure B is basically the same as Procedure A described above,except that the extrusion temperature was 280 to 350° C., the polymerthroughput rate was about 66 kg/hr, and the monoglyceride wasincorporated into the polymer melt stream just before the die, asdescribed in U.S. Pat. No. 4,933,229 (Insley et al.) and U.S. Pat. No.5,064,578 (Insley et al.). The monoester throughput rate was about 2kg/hr and the die width was about 152 cm.

Spunbond Extrusion Procedure

The extruder used was a Reifenhauser Extruder Model Number RT 381(available from Reifenhauser Co., Troisdorf, Nordrheim Westfalen,Germany), 2.34 m in length×1.335 m in width×1.555 m in height, weighing2200 kg. The extruder was driven by an infinitely variable shunt woundDC motor, 37.3 kW and 2200 rev/min max. The maximum screw speed wasreduced to 150 rev/min. The screw was 70 mm in diameter and 2100 mm inlength. The extruder had five 220 V heating zones using a total of 22.1kW of heating power. The metering pump delivered 100 cm³ of polymer meltper revolution. The die had seven adjacent heating zones. The spinneretwas approximately 1.2 meters wide and had 4036 holes, each hole of 0.6mm diameter and 2.4 mm in length. The extrusion temperature reported wasthe temperature in the die block before the polymer melt stream wasdistributed along the die. The maximum throughput of the die was 104kg/h, or 0.43 g/hole/min. The cooling chamber operated with an airtemperature of 18.3° C. and a cooling air speed of 1000 to 3000 m/min.

The bonder used to bond the spunbond fibers into a fabric was a KustersTwo-Bowl-Thermobonding-Calender (available from Kusters Corp., NordrheimWestfalen, Germany). The effective bonding width was 1.2 m. The upperpatterned metal roll had a 14.66% bonding area and a temperature of270-285° F. (132-141° C.), while the lower rubber roll had a slicksurface and a temperature of 265-280° F. (129-138° C.). The bonding nippressure was 57-750 pounds force per linear inch (3000-41000 J/cm). Theheating of the rolls was done by convection from a continuouslycirculating furnace oil. The temperature of the nips was 200-300° F.(93-149° C.). The speed of the bonder was directly synchronized to thespeed of the collection belt that had a range of 3.6 to 65 linear metersper minute.

The basis weight for each nonwoven fabric (g/m²) was calculated bymultiplying the speed of the spin pump (rev/m) times the constant 71.For all examples, the basis weight used was approximately 20 g/m².

Hydrophilicity Test

The Hydrophilicity Test was run by holding the outside surface (sideopposite the collector) a rectangular nonwoven web sample approximately8×11 inches (20×28 cm) under a stream of either hot (approximately45°±2° C.) or cold (approximately 25°±2° C.) tap water with a volumeoutput of approximately 200 ml/min at a distance of about 1 inch (2.5cm) from the water spigot. The nonwoven web sample was held with thumbsdownward on top of the center of each 8 inch (20 cm) side edge andfingers upward underneath the web sample pointed toward the center ofthe sample for support, and tilting the web slightly so that the far 11inch (28 cm) edge was slightly higher than the near 11 inch (28 cm)edge. Each nonwoven web sample had a basis weight of 50±5 g/m², aneffective fiber diameter of 8 to 13 microns (as calculated according tothe method set forth in Davies, C. N., “The Separation of Airborne Dustand Particulates,” Institution of Mechanical Engineers, London,Proceedings 1B, 1952), and a web solidarity of 5 to 15%. The followingnumber scale was used to rate the hydrophilicity of each web sample:

-   -   1 immediate wetting (web sample goes from being completely        opaque to completely translucent);    -   2 wetting delayed for about 0.5 to 2.0 seconds (web sample goes        from being completely opaque to completely translucent);    -   3 wetting delayed from greater than 2.0 seconds to about 10        seconds (web sample goes from being completely opaque to        completely translucent);    -   4 wetting delayed from greater than 2.0 seconds to about 10        seconds, but wetting occurs only where the web sample contacts        the hand placed under the sample;    -   5 no wetting at all (i.e., the web sample remains opaque).        Where the degree of wetting varied across the width of the web        sample, a set of several number values was recorded,        representing values measured in a direction perpendicular to the        machine direction from one side of the web sample to the other.        For example, in one case, the first 40% of the distance across        the web sample showed a reading of “1”, the next 20% of the        distance across the web sample showed a reading of “5”, and the        final 40% of the distance across the web sample showed a reading        of “2”. The reported rating for this web would be the weighted        average of the values or (0.40)(1)+(0.20)(5)+(0.40)(2)=2.2.

A value (either single or weighted average) of no greater than 3 forboth hot and cold water is preferred.

Percent Wet Pickup Test

A 12 inch (30 cm) long×8 inch (20 cm) wide by 2 inch (5 cm) deep pan wasfilled with 2 liters of tap water having a temperature of 25±2° C.Nonwoven melt blown fabric web samples having a target basis weight of 9to 10 grams per square meter were each cut to a rectangular shape of6.5±0.5 inches by 11.5±1 inch and weighed 2.4±0.3 grams. Eachrectangular web sample was weighed to the nearest hundredth gram on abalance to give the Fabric Dry Weight. The web sample was placed flatupon the water surface for 5±2 seconds, then was removed from the watersurface and was allowed to drip excess water for 5±2 seconds. Thewetted, drained web sample was weighed again to the nearest 0.01 gram togive the Fabric Wet Weight. The Percent Wet Pickup was calculated usingthe formula:

${{Percent}\mspace{14mu}{Wet}\mspace{14mu}{Pickup}} = {\frac{\left( {{{Fabric}\mspace{14mu}{Wet}\mspace{14mu}{Weight}} - {{Fabric}\mspace{14mu}{Dry}\mspace{14mu}{Weight}}} \right)}{{Fabric}\mspace{14mu}{Dry}\mspace{14mu}{Weight}} \times 100}$The test was repeated on five different samples for each test web, sothat each Percent Wet Pickup value reported is the average of fivereplications. The standard deviation is given for each set of fivereplications.Percent Water Absorbency Test

Evaluation of the percent water absorbency of various materials of thisinvention was measured using the following test procedure. For eachtest, a 7.62 cm×7.62 cm sample having a target basis weight of 9 to 10grams per square meter was weighed, placed on the surface of tap waterat 32°±2° C. for one minute, and then removed from the surface of thewater by holding up a corner of the pad with the smallest possible area.When the sample used was a pad having a waterproof side, the absorbentside (i.e., netting side) of the pad was placed down on the watersurface. The excess water was allowed to drip off from one corner of thepad for 30±2 seconds, still holding a corner of the pad with thesmallest possible area. The sample was then weighed again. The percentwater absorbency of the sample was then calculated using the formula:

${{Percent}\mspace{14mu}{Water}\mspace{14mu}{Absorbency}} = {\frac{\begin{pmatrix}{{{Wet}\mspace{14mu}{Sample}\mspace{14mu}{Weight}} -} \\{{Dry}\mspace{14mu}{Sample}\mspace{14mu}{Weight}}\end{pmatrix}}{{Dry}\mspace{14mu}{Sample}\mspace{14mu}{Weight}} \times 100}$

Each Percent Water Absorbency reported value is the average of 8-10replications.

Drop Wetting Test

The hydrophilicity of the outside surface (side opposite the collectorbelt) of spunbond fabrics was measured using the following drop wettingtest procedure. A 10 cm by 20 cm piece of spunbond fabric, having abasis weight of approximately 20 g/m² unless otherwise noted, was placedon a double folded paper towel, and the fabric was smoothed by hand tobe in as intimate contact as possible with the paper towel. Next, 10drops of 0.9% aqueous NaCl having a temperature of 25±3° C. and about6-8 mm in diameter were gently placed on the fabric at least 8 mm apart.After 10 seconds, the number of drops that are completely absorbed fromthe surface of the nonwoven into the paper towel was recorded. Valuesprovided in the examples are each an average of three such dropabsorption trials.

Antimicrobial Test

The materials of this invention were cut into 3.8 cm×3.8 cm squaresamples and evaluated for antimicrobial activity according to theAmerican Association of Textile and Color Chemists (AATCC) Test Method100-1993, as published in the AATCC Technical Manual, 1997, pages143-144. Modifications to the Test Method included the use of TrypticSoy Broth as the nutrient broth and for all dilutions and Tryptic SoyAgar as the nutrient agar. Letheen Broth (VWR Scientific Products,Batavia, Ill.) was used as the neutralizing solution.

EXAMPLES Examples 1-13 and Comparative Examples C1-C15

In Examples 1 to 7, the initial wettability of nonwoven webs preparedusing Melt-Blown Extrusion Procedure A to extrude EOD 96-36polypropylene with various melt additives was determined.

Examples 1 to 7 were prepared using concentrations of GML varying from 1to 4% by weight (based on polymer weight). Examples 8-13 were preparedusing various monoglycerides of relatively high purity at 3% by weight.Comparative Example C1 was prepared using glycerol monostearate at 3% byweight. Comparative Examples C5 to C8 were prepared using less puregrades of glycerol monoesters. Comparative Examples C2 and C3 wereprepared using different fluorochemical nonionic surfactants andComparative Example C4 was prepared using a silicone surfactant.Comparative Examples C9 to C13 were prepared using various otherhydrocarbon surfactants, including PEG di- and monoesters, analkylphenol ethoxylate, an alcohol ethoxylate, and a phenoxy arylalkylphenol ethoxylate. Comparative Examples C14 and C15 were preparedwithout a melt additive. It should be noted that Examples 8-10 andComparative Example C15 were prepared using the same Melt-BlownExtrusion Procedure A outlined above, but at an extrusion temperature of220° C. instead of 255° C. A rating of hydrophilicity for each nonwovenweb was determined using the Hydrophilicity Test. A description of thesamples and their Hydrophilicity Test results are summarized in Table 2.

Also included in Table 2 is an analysis of weight percent monoglyceride,where applicable, for each additive.

TABLE 2 Monoglyceride in Surfactant 1 Surfactant 1 (wt. Cold Water HotWater Ex. (wt. %) %) Rating Rating  1 GML (1.0%) 94 5.0 3.4  2 GML(1.25%) 94 4.4 1.9  3 GML (1.5%) 94 2.3 1.3  4 GML (2.0%) 94 1.4 1.0  5GML (2.5%) 94 1.3 1.0  6 GML (3.0%) 94 1.0 1.0  7 GML (4.0%) 94 1.0 1.0 8* GML (3.0%) 94 1.0 1.0  9* GM-C8 (3.0%) 88.8 1.7 1.4 10* GM-C10 89.11.0 1.0 (3.0%) 11 GM-C12 90.5 1.2 1.0 (3.0%) 12 GM-C14 88.4 2.7 1.0(3.0%) 13 GM-C16 93.8 4.4 1.0 (3.0%) C1 GM-C 18 87.0 5.0 3.2 (3.0%) C2FS-1 (1.25%) N/A 1.0 1.0 C3 FS-2 (1.25%) N/A 3.0 1.0 C4 SS-1 (3.0%) N/A5.0 3.0 C5 HS-1 (3.0%) 44.5 5.0 4.6 C6 HS-2 (3.0%) 50.9 5.0 5.0 C7 HS-3(3.0%) 56.5 5.0 5.0 C8 HS-4 (3.0%) N/M 5.0 5.0 C9 HS-5 (3.0%) N/A 5.05.0 C10 HS-6 (3.0%) N/A 5.0 3.3 C11 HS-7 (3.0%) N/A 5.0 5.0 C12 HS-8(3.0%) N/A 5.0 4.0 C13 HS-9 (3.0%) N/A 5.0 5.0 C14 — N/A 5.0 5.0 C15* —N/A 5.0 5.0 N/M: means not measured N/A: means not applicable becausematerial did not contain monoglyceride *means extruded at 220° C. ratherthan the usual 270-280° C.

The data in Table 2 show that samples prepared using GML provided goodwettability even at GML levels as low as 1.5% in the polymer. At the 3%level, excellent wettability to both cold and hot water resulted, andthe overall performance of the sample favorably compared to samplesprepared using FS-1, a more expensive hydrophilic fluorochemicaladditive. Even at some levels less than 3%, GML outperformed SS-1, ahydrophilic silicone surfactant.

The data also show that materials containing monoglycerides derived fromC₈, C₁₀, C₁₀, C₁₂, C₁₄ and C₁₆ carboxylic acids (HLB values of 8.3, 7.4,6.3, 6.2, 5.3 and 4.5 respectively) also imparted improved wettabilityto nonwoven webs. However, materials containing monoglycerides derivedfrom C₁₈ carboxylic acid provided only slightly better hot water wettingthan the control.

The effect of the concentration of monoglyceride in the surfactantmaterial is illustrated by comparing Examples 6 and 11 (prepared fromGML and GM-C 12, which have glycerol monolaurate contents of 94 and90.5% and calculated HLB values of 6.3 and 6.2, respectively) withComparative Example C5 (prepared with HS-1 having a glycerol monolauratecontent of 44.5% and a calculated HLB value of 4.3). The samples shownin Examples 6 and 11 provided improved wettability over the control.However, the Comparative Example C5 sample did not. In part, this wasattributable to the lower concentration of monoglyceride in theComparative C5 sample. Also, even quite pure materials, like GM-C18 (87%glycerol monomyristate, HLB value of 3.0), are not as effective atimparting wettability to the nonwoven web as monoglycerides derived fromcarboxylic acids with optimum chain lengths. Thus, the HLB value whichaccounts for both monoglyceride content and type of monoglyceride can bean excellent predictor of whether commercially available monoglyceride,diglyceride, triglyceride and glycerol mixtures will function at theconcentrations most desired for cost effectiveness and processability.The data show that additive materials containing monoglycerides andhaving HLB values of about 4.5 to 9.0 will improve wettability over thecontrol.

HS-5 and HS-6 which are mixtures of di- and mono-fatty acid esters ofpolyethylene glycol, did not significantly improve the wettability ofnonwoven webs over the control.

Examples 14 to 18 and Comparative Examples C16 to C20

In Examples 14 to 18 and Comparative Examples C16 to C20, polybutylene(PB 0400) was evaluated as a hydrophilic enhancer for varioushydrocarbon surfactants. In all Examples and Comparative Examples,polypropylene EOD 96-36 and the Melt-Blown Extrusion Procedure A wereused to prepare the nonwoven web samples and the Hydrophilicity Test wasused to evaluate the initial wettability of each of the nonwoven webs.

A description of the samples and their results from the HydrophilicityTest are presented in Table 3.

TABLE 3 Hydrocarbon PB 0400 Cold Water: Hot Water: Ex. Surfactant (wt.%) (wt. %) Rating Rating 14 GML (1.0%) 5 3.6 1 14 GML (1.0%) — 5 3.4control 15 GML (1.5%) 5 1 1 15 GML (1.5%) — 2.3 1.3 control 16 GML(2.0%) 5 1 1 16 GML (2.0%) — 1.4 1 control C16 HS-1 (1.5%) + HS-7 5 54.8 (1.5%) C16 HS-1 (1.5%) + HS-7 — 5 5 Control (1.5%) C17 HS-3 (1.5%) +HS-7 5 5 2.9 (1.5%) C17 HS-3 (1.5%) + HS-7 — 5 4.4 Control (1.5%) C18HS-1 (3.0%) 5 5 2.3 C18 HS-1 (3.0%) — 5 4.3 Control 17 GM-C12 (2.0%) 5 11 18 GM-C14 (3.0%) 5 2 1 C19 GM-C 18D (2.0%) 5 4.5 2 C20 HS-7 (3.0%) — 55 Control C20 HS-7 (3.0%) 5 5 5

The data in Table 3 show that polybutylene enhanced the wettability ofthe polypropylene webs containing glycerol monoesters with HLB valuesranging from 5.3 to 8.3 versus the controls (no polybutylene).Polybutylene did not significantly enhance wettability when combinedwith glycerol monoesters having HLB values of less than 5 in combinationwith an ethoxylated alkylphenol surfactant. Polybutylene also did notenhance the wettability of webs prepared using only an ethoxylatedoctylphenol surfactant.

Re-Testing of Selected Webs from Tables 1 and 2 after Aging at RoomTemperature

The nonwoven webs from Examples 6, 8, 10, 14, 15, 16 and 17 werereevaluated for wettability using the Hydrophilicity Test after agingunder ambient lab conditions for a period of 4-5 months (also after 2months for Examples 6 and 15). The wetting values, initially and afteraging, are presented in Table 4.

TABLE 4 Cold Water (initial and Hot Water (initial and Hydrocarbon PB0400 after aging) after aging) Ex. Surf. (wt. %) (wt. %) Init. 2 mos.4-5 mos Init. 2 mos. 4-5 mos.  6 GML (3.0%) — 1 3 4 1 1 1  8* GML (3.0%)— 1 N/R 5 1 N/R 1  10* GM-C10 — 1 N/R 3 1 N/R 1 (3.0%) 14 GML (1.0%) 5.03.6 N/R 4 1 N/R 1 15 GML (1.5%) 5.0 1 4 4 1 1 1 16 GML (2.0%) 5.0 1 N/R4 1 N/R 1 17 GM-C12 5.0 1 N/R 5 1 N/R 1 (2.0%) *means extruded at 220°C. rather than the usual 270-280° C. N/R: means not recorded

The data in Table 4 show that the wettability of the polypropylene websto cold water decreased after storage for 4-5 months, even whenpolybutylene was present.

Examples 19-23 and Comparative Examples C21-C23

A series of experiments was run to investigate the effect of using SPAN™20 (sorbitan monolaurate) or SPAN™ 40 (sorbitan monopalmitate) incombination with GML and polypropylene to improve the hydrophilicity ofthe extruded webs after aging. In all Examples and Comparative Examples,polypropylene EOD 96-36 and the Melt-Blown Extrusion Procedure A wereused to prepare the nonwoven web samples and the Hydrophilicity Test wasused to evaluate the wettability of each nonwoven web, both initiallyand after aging for 23 days under ambient conditions.

Results from the Hydrophilicity Test are presented in Table 5.

TABLE 5 Cold Water Hot Water: After After wt %: Aging Aging Ex. wt % GMLSpan 20 Span 40 Init. 23 days Init. 23 days C21 — — — 5 5 5 5 19 3   — —1 4 1 1 20 2.25  0.75 — 1 1 1 1 21 1.5  1.5 — 5 2.7 1 1 C22 — 3.0 — 5 41.7 1 22 2.25 —  0.75 1 1 1 1 23 1.5  — 1.5 2.7 1 2 1 C23 — — 3.0 5 3.35 4

The data in Table 5 show that GML in combination with either SPAN™ 20 orSPAN™ 40 produced nonwoven webs with superior hydrophilicity afteraging. Optimum hydrophilicy before and after aging occurred at 25%replacement of the GML with either SPAN™ 20 SPAN™ 40. Also, SPAN™ 20 andSPAN™ 40 acted as an extender, allowing for 25% substitution of the moreexpensive GML component.

Example 24-32 and Comparative Examples C24-C25

A series of experiments was run to investigate mixtures of PB 0400polybutylene, various sorbitan esters, and GML as polymer melt additivesfor polypropylene. In all Examples and Comparative Examples,polypropylene EOD 96-36 and the Melt-Blown Extrusion Procedure A wereused to prepare the nonwoven web samples, and the Hydrophilicity Testwas used to evaluate the wettability of each nonwoven web, bothinitially and after aging under ambient conditions. The web samplescontaining SPAN™ 20 (sorbitan monolaurate) were aged for 10 days at roomtemperature, while the web samples containing ARLACEL™ 60 (sorbitanmonostearate) and ARLACEL™ 83 (sorbitan sequioleate) were aged for 7days at room temperature.

Results from the Hydrophilicity Test are presented in Table 6.

TABLE 6 Sorbitan Ester Hot (SPAN ™/ Water: ARLACEL ™): Cold Water: AfterGML Product PB0400 After Ag- Ex. wt % Number wt % wt % Init. Aging Init.ing 24 1.8 20 0.2 — 1.7 3.7 1 1 25 1.8 20 0.2 5 1 3 1 1 26 1.4 20 0.6 —1.7 3.7 1 1.7 27 1.4 20 0.6 5 1 2 1 1 28 2.1 20 0.9 — 1 3 1 1 29 2.1 200.9 5 1 2 1 1 30 1.05 60 0.45 5 3.3 4 1 1 C24 — 60 1.5 5 5 5 5 5 31 1.0583 0.45 5 3.3 4 1 1 C25 — 83 1.5 5 3.7 5 2 2 32 1.05 20 0.45 11.58 1 N/R1 N/R 32A 0.975 20 0.525 7.5 2 N/R 1.2 N/R 32B 0.975 20 0.525 3.5 3.7N/R 3 N/R 14 1 — — 5 3.6 — 1 — N/R = not run

The data in Table 6 show that the addition of 5% polybutylene to blendsof GML and SPAN™ 20 generally improved the cold water hydrophilicity ofthe web, both before and after aging. Neither ARLACEL™ 60 or ARLACEL™ 83appeared to offer any particular benefit when incorporated with the GML(compare initial results from Examples 30 and 31 with Example 14included for reference). GML levels could be reduced to nearly 1% whenthe PB 0400 level was increased to greater than 10% and the SPAN™ 20level was under 0.5% (Example 32).

The aged webs from Example 30 and Comparative Example C24 were testedagain according to the Hydrophilicity Test after aging for a total ofabout 7 months. Hot water values were 2 and 5, respectively, while coldwater values were 5 and 5, respectively.

Examples 33-49 and Comparative Example C26

A series of experiments was run to investigate the optimum weight ratioof GML to SPAN™ 20 or SPAN™ 40 when used in conjunction with 5% PB 0400polybutylene as a polymer melt additive to polypropylene. In allExamples and the Comparative Example, polypropylene EOD 96-36 and theMelt-Blown Extrusion Procedure A were used to prepare the nonwoven websamples and the Hydrophilicity Test was used to evaluate the wettabilityof each nonwoven web, both initially and after aging for 10 days underambient conditions.

Results from the Hydrophilicity Test are presented in Table 7.

TABLE 7 Cold Water: Hot Water: SPAN ™ GML to After After GML + SPAN ™monoester SPAN ™ PB Aging Aging monoester Product monoester 0400 10 10Ex. wt % No. Ratio wt % Init. days Init. days C26 — — — — 5 5 5 5 33 3 —infinite — 1 3.8 1 1 34 2 20 90/10 5 1 3.8 1 1 35 2 20 70/30 5 1 1 1 136 1.75 20 90/10 5 1 5 1 1 37 1.75 20 50/50 5 1 1 1 1 38 1.5 20 70/30 51 1 1 1 39 1.5 20 50/50 5 1 1 1 1 40 1 20 90/10 5 1 4 1 1 41 1 20 70/305 1 1 1 1 42 1 20 50/50 5 1 1 1 1 43 2 40 90/10 5 1 2 1 1 44 2 40 50/505 3 4 1 1 45 1.75 40 90/10 5 1 2.7 1 1 46 1.75 40 70/30 5 1 3 1 1 47 1.540 90/10 5 1 4 1 1 48 1.5 40 70/30 5 1 1.7 1 1 49 1.5 40 50/50 5 2 2.7 11

The data in Table 7 shows that, in a 1-2% concentration range of GMLplus SPAN™ 20 monoester, replacement of GML with 10% of SPAN™ 20monoester does not greatly improve the cold water hydrophilicity afteraging of the meltblown webs. However, replacement of GML with 30% or 50%of SPAN™ 20 monoester clearly enhances the cold water hydrophilicityafter aging of the webs. Additionally, SPAN™ 20 monoester is moreeffective than SPAN™ 40 monoester in improving the cold waterhydrophilicity after aging of the webs.

Examples 50-69 and Comparative Examples C27-C29

A ladder experiment was run to determine the effective use levels ofGML, SPAN™ 20 (SML) and PB 0400 polybutylene (PB) in EOD 96-36polypropylene. GML levels were varied from 0-2% and SPAN™ 20 levels werevaried from 0-2% so that the total of the two levels was kept at 2%.Meanwhile, the level of PB was kept constant at 7.5% in all cases exceptfor Comparative Example C29, which was run with polypropylene alone.Extrusion was done using Melt-Blown Extrusion Procedure A, and theresulting webs were evaluated for hydrophilicity using theHydrophilicity Test (both Cold Water and Hot Water) and the Percent WetPickup Test, both described above. Web samples were evaluated initiallyand after aging for 2000 hours at room temperature. Results from theseevaluations are presented in Table 8.

TABLE 8 Percent Wet Cold Hot Pickup: Water: Water: Ex. % GML % SML % PBInitial Aged Init. Aged Init. Aged 50 2.0 — 7.5 745 ± 44 238 ± 23 1 4 11 51 1.9 0.1 7.5 809 ± 30 276 ± 70 1 4 1 1 52 1.8 0.2 7.5 773 ± 33 174 ±34 1 4 1 1 53 1.7 0.3 7.5 749 ± 24 369 ± 41 1 3 1 1 54 1.6 0.4 7.5 751 ±22 298 ± 47 1 3 1 1 55 1.5 0.5 7.5 749 ± 32 268 ± 23 1 3 1 1 56 1.4 0.67.5 753 ± 30 490 ± 48 1 2 1 1 57 1.3 0.7 7.5 1004 ± 17  666 ± 64 1 2 1 158 1.2 0.8 7.5 711 ± 14 627 ± 46 1 1 1 1 59 1.1 0.9 7.5  838 ± 104 709 ±23 1 1 1 1 60 1.0 1.0 7.5 800 ± 28 615 ± 15 1 1 1 1 61 0.9 1.1 7.5 831 ±25 563 ± 18 1 1 1 1 62 0.8 1.2 7.5 878 ± 40 644 ± 16 2 1 1 1 63 0.7 1.37.5 868 ± 37 641 ± 20 1 2 1 1 64 0.6 1.4 7.5  737 ± 112 665 ± 38 4 1.7 21 65 0.5 1.5 7.5 626 ± 55 655 ± 27 4 1 2 1 66 0.4 1.6 7.5 229 ± 36 605 ±16 4 1.3 3 1 67 0.3 1.7 7.5 188 ± 43 706 ± 17 5 1.3 3 1 68 0.2 1.8 7.5247 ± 68 568 ± 10 5 2.3 3 1.3 69 0.1 1.9 7.5 162 ± 31 659 ± 43 5 3 5 1.7C27 — 2.0 7.5 118 ± 37 381 ± 15 5 4.3 4 2 C28 — — 7.5  6 ± 4 11 ± 8 5 55 5 C29 — — —  9 ± 6  15 ± 20 5 5 5 5

Based on the results from both tests, the data in Table 8 show thatsubstitution of GML with at least 15% SPAN™ 20 led to improvement incold water absorption after the web sample had aged. Based on theHydrophilicity Test results, overall optimum wetting seemed to occurwhen about 40-60% of the GML was substituted with SPAN™ 20.Interestingly, hydrophilicity often improved after aging in web samplescontaining higher percentages of SPAN™ 20.

Examples 70 to 72

In Examples 70 to 72, compositions containing both GML and HS-1(glycerol monolaurates of high and low purity, respectively) at variousweight ratios were evaluated in polypropylene EOD 96-36 using Melt-BlownExtrusion Procedure A. The Hydrophilicity Test was used to evaluate thewettability of each nonwoven web. A description of the hydrocarbonsurfactant compositions, their monoglyceride content, calculated HLBvalues and wettability data are presented in Table 9.

TABLE 9 Hydrocarbon Surfactants and Cold Hot Amounts Monoglyceride WaterWater HLB Value Example (wt. %) (wt. %) Rating Rating Surfactant 70(1.5%) GML + (1.5%) 69.25 4.5 2 5.3 HS-1 71 (2.25%) GML + (0.75%) 81.6252.2 1 5.8 HS-1 72 (2.44%) GML + (0.56%) 84.71 2 1 5.93 HS-1

The data in Table 9 show that very good cold water wettability can beachieved using the described combinations of surfactants provided theoverall HLB values of the surfactant combinations were kept betweenabout 5.8 and 5.93 (corresponds to a monoglyceride content of at least81.6 wt. % and 84.7 wt. % respectively).

Examples 73 to 75 and Comparative Example C30

Four films were produced from the nonwoven webs of Examples 6 and 15,and Comparative Examples C5 and C15. The fabrics were melted at 200° C.in a platen press and then pressed with an applied force of ten tons forabout 45 seconds. The samples were then allowed to air cool under thesame pressure. The resulting films were all seven mils (0.3 mm) thick.

A test was run to determine the anti-fog properties of the four samplefilms. The test was performed as follows: Firstly, four four-ounce glassjars were filled with warm water (approximately 30° C.) to just belowthe neck. A silicone sealant (Cling 'n Seal RTV siliconeadhesive/sealant) was applied to the top of the jar. Each film samplewas placed on top of a jar to act as a lid, and then the four jars wereleft for fifteen minutes at ambient conditions to let the sealant setup. All of the film samples with jars were then placed into an oil-baththat was heated to 50° C. Data were then collected periodically as toamount of water that had collected on the bottom of each film. Resultsare shown in Table 10.

TABLE 10 Film Sample Condensation on Film at Designated Time ExampleComponents and Amounts (wt. %) 5 min. 30 min. 1 hr. 2 hrs. C30 (100%)Polypropylene Control Fogged over Fine drops Small drops Small dropswith vapor 73 (97%) Polypropylene + (3%) HS-1 Very fine drops Smalldrops Large drops Large drops 74 (97%) Polypropylene + (3%) GML Smalldrops Large drops Large drops Large drops 75 (93.5%) Polypropylene +(1.5%) GML + (5%) Large drops Large drops Large drops Large dropsPolybutylene PB 0400

The data in Table 10 show that one cannot distinguish the anti-fogproperties in films containing HS-1 at 3%, GML at 3%, and GML at 1.5%+5%Shell PB0400 polybutylene. However, data on the cold water wettabilityof webs prepared using the same extrudable compositions (see Table 2)show that the wettability of webs prepared from compositions containing3% GML or 1.5% GML+5% Polybutylene PB 0400 had a significantly bettercold water wetting rating (i.e., 1) than a web prepared from acomposition containing 3% HS-1 (i.e., 5).

Example 76

This Example illustrates the preparation of an absorbent deviceaccording to the invention. A melt-blown nonwoven web of polypropylenewas prepared from a polymer/monoester blend of Fina 3960X polypropyleneand 3.0% by weight of GML using the Melt Blown Extrusion Process B,described herein. The resulting web (basis weight 130 g/m²) was combinedwith cellulose pulp (basis weight 40 g/m²) commercially available fromInternational Tray Pads and Packaging, Inc. of Aberdeen, N.C. as 7 plyHibulk Paper Web using a process similar to that described in U.S. Pat.No. 4,100,324 (which disclosure is incorporated by reference herein) togive a finished nonwoven absorbent web material.

A three-layer absorbent device was then prepared by laminating togetherthe above finished web material with a liquid-impermeable polypropylenebacking sheet prepared according to the method described in U.S. Pat.No. 4,726,989 (Mrozinski), (Example 1 without the solvent extraction ofthe oil) on one side and a liquid-permeable non-stick netting (CKX215P-S Netting, commercially available from Applied Extrusion Technologies,Middletown, Del.) on the other side. The lamination was carried outusing hexagonal honeycomb patterned rolls heated to 132° C. and gappedat 0.12 to 0.25 mm. The dressing was observed to immediately absorbbody-temperature water on the side with the non-stick netting.

Examples 77 to 81

These Examples illustrate the antimicrobial activity of nonwoven websused to prepare the absorbent devices.

Melt-blown nonwoven webs were prepared using PP3505 polypropylene andvarious amounts of GML using a process similar to the Melt-BlownExtrusion Process B except with a flow rate of 0.45 Kg/hr and atemperature range of 250° C. to 280° C. In the case of Example 77, theresulting web was further combined with cellulose pulp using a processand a material similar to that described in Example 76. In Example 81,following extrusion of the hot polymeric fibers, an aqueous solution ofLA was sprayed onto the fibers to achieve a level of 1.5% (based on thetotal weight of the coated and dried web). The heat of the polymerevaporated the water and left the lactic acid intimately in contact withthe GML-containing fibers.

The resulting webs were then evaluated for antimicrobial activity usingthe Antimicrobial Test and Staphylococcus aureus. The concentrations ofGML used to prepare the Examples, the web basis weights and the webantimicrobial activities are summarized in Table 11. The antibacterialdata in Table 11 are percent reductions in bacterial colony formingunits (CFU) after a 24-hour exposure time at 23-24° C. These data showthat all test samples possessed bactericidal activity although thematerial treated with lactic acid after extrusion showed the greatestpercent kill of S. aureus.

TABLE 11 GML Lactic Acid Reduction of Bacterial Web Basis Example (%)(%) CFU (%) Wt. (g/m²) 77 2.0 0 98.63 103 78 2.0 0 99.91 68 79 1.0 096.83 52 80 1.5 0 94.48 52 81 2.0 1.5 99.99 65

Examples 82-86

These Examples illustrate the degree of water absorbency of variousnonwoven web constructions of this invention.

In Examples 82-84, melt-blown polypropylene nonwoven webs were preparedusing PP3505 polypropylene and various amounts of GML using a processsimilar to the Melt-Blown Extrusion Process B, except that the monoesterthroughput rate was about 6.8 kg/hr and the die width was about 51 cm.

In Example 85, a melt-blown polypropylene nonwoven web was preparedusing PP3746 polypropylene, 7.5% PB 0400 polybutylene, and 2.0% GMLusing a process similar to the Melt-Blown Extrusion Process B, exceptthat the monoester throughput rate was about 9.1 kg/hr and the die widthwas about 51 cm.

In Example 86, a sample of the three-layer absorbent device prepared asgenerally described in Example 76 was employed. The nonwovenpolypropylene web component was made using 3.0% GML and had a resultingbasis weight of 130 g/m². The average dry weights of the individualcomponents of a 7.62 cm×7.62 cm sample of the device were 0.16 g(netting), 0.13 g (film backing), and 0.96 g (absorbentpolypropylene/cellulose pulp core).

The amount of water absorbed, and the percent water absorbency of 7.62cm×7.62 cm samples of Examples 82-86 were measured according to thePercent Water Absorbency Test described above. Results are provided inTable 12.

TABLE 12 GML Water Absorbed Percent Water Example (%) (g) Absorbency (%)82 3.0 10.29 1278 83 4.0 9.62 1177 84 5.0 10.14 1254 85 2.0 9.90 1127 863.0 11.47  919* *Percent Water Absorbency = 1211% based on dry weight ofthe device less the dry weight of netting and film components.

The data in Table 12 show that all samples were highly water absorbentwith each sample capable of absorbing over ten times its own weight withwater. For these Examples, there was not a significant correlationbetween % water absorbency and levels of GML present in the samples.

Examples 87-89 and Comparative Example C31

These examples illustrate the hydrophilicity of various spunbond fabricsof this invention.

Using the Spunbond Extrusion Procedure with minor modifications,spunbond fabrics containing various percentages of GML, PB 0400polybutylene and/or SPAN™ 20 in EXXON™ 3155 polypropylene were prepared.

In Example 87, the extruded polymer mixture consisted of 93.5% 3155,1.5% GML and 5% PB 0400.

In Example 88, the extruded polymer mixture consisted of 88.5% 3155,1.05% GML, 0.45% SPAN™ 20 and 10% PB 0400.

In Example 89, the extruded polymer mixture consisted of 86.2% 3155,1.65% GML, 0.85% SPAN™ 20 and 11.33% PB 0400.

In Comparative Example C31, the extruded polymer mixture consisted of95% 3155 and 5% PB 0400 (no hydrophilic additive).

The fabrics were tested for hydrophilicity using the Drop Wetting Test.Results from these tests are shown below in Table 13.

TABLE 13 Processing Conditions: Ex. 87 Ex. 88 Ex. 89 C. Ex. C31 MeltTemp. (° C.) 199 207 227 196 Throughput (g/hole/min) 0.15 0.15 0.25 0.15Basis Weight (g/m²) 20 20 17 20 No. of Drops/10 Absorbed 3 5 4 0

The data in Table 13 show that all of the spunbond samples containingGML (Examples 87-89) demonstrated hydrophilicity, while the samplewithout the GML (Comparative Example C31) was hydrophobic.

Examples 90-109 and Comparative Example C32

These examples illustrate the use of various polymer additives at the10% level to improve the hydrophilicity of melt-blown web samples madeof EOD 96-36 polypropylene containing GML and 70/30 blends of GML/SPAN™.Extrusion was done using Melt-Blown Extrusion Procedure A, and theresulting web samples were evaluated for initial hydrophilicity to hotand cold water using the Hydrophilicity Test. Results from theseevaluations are presented in Table 14.

TABLE 14 Polymer Cold Hot Ex. % GML % SPAN ™ 20 Additive Water Water C32— — — 5 5  90 1 — — 4.3 5  91 1.25 — — 4.3 3.6  92 1.5 — — 2 3  93 2 — —1.3 1.7  94 2 — PB 0400 1 1  95 1.25 — PB 0400 1 1  96 1.25 — DP-8340 11  97 1.25 — 8401 1 1  98 1.25 — 8402 1 1  99 1.25 — 4023 1 1 100 1.25 —8910 1 1 101 1.4 0.6  — 2 2.3 102 1.23 0.52 — 2.3 3 103 1.05 0.45 — 2.33 104 1.05 0.45 PB 0400 1 1 105 1.05 0.45 DP-8340 1 1.2 106 1.05 0.45DP-8910 1 1 107 1.05 0.45 4023 1 1 108 1.05 0.45 8401 1 1 109 1.05 0.458402 1 1The data in Table 14 shows that the polyolefinic hydrophilic enhancersall improved the hydrophilicity of the nonwoven web samples.

The complete disclosures of the patents, patent documents, andpublications cited herein are hereby incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited solely by the claims set forth herein as follows.

1. A polypropylene fiber having incorporated therein (a) a C₈ to C₁₆fatty acid monoglyceride or a mixture of glycerides containing at least80 percent by weight of one or more C₈ to C₁₆ fatty acid monoglycerides,and (b) a hydrophilic enhancer material selected from the groupconsisting of polybutylene, polybutylene copolymers, ethylene/octenecopolymers, and atactic polypropylene; wherein the surface of the fiberis treated with an effective amount of an antimicrobial enhancermaterial such that the fiber is antimicrobial to Gram-negative bacteria,and wherein the antimicrobial enhancer material is an organic acid or achelating agent.
 2. The fiber of claim 1 wherein the monoglyceride isselected from the group consisting of a glycerol monocaprylate, glycerolmonocaprate, and glycerol monolaurate.
 3. The fiber of claim 1 whereinthe monoglyceride comprises a mixture of at least two monoglyceridesselected from the group consisting of a glycerol monocaprylate, aglycerol monocaprate, and a glycerol monolaurate.
 4. The fiber of claim1 wherein the polybutylene is incorporated prior to fiber formation inan amount from about 2 to about 25 weight percent.
 5. The fiber of claim1 wherein the polybutylene is incorporated prior to fiber formation inan amount from about 5 to about 15 weight percent.
 6. The fiber of claim1 wherein the monoglyceride is a C₈ to C₁₂ fatty acid monoglyceride. 7.The fiber of claim 6 having an effective amount of the monoglycerideincorporated therein such that the fiber is antimicrobial toGram-positive bacteria.
 8. The fiber of claim 1 wherein theantimicrobial enhancer material is lactic acid.
 9. A polypropylene fibercomprising: (a) polypropylene; (b) an effective amount of a C₈ to C₁₂fatty acid monoglyceride incorporated into the fiber to impart bothhydrophilicity and antimicrobial activity to Gram-positive bacteria tothe surface of the fiber; (c) a hydrophilic enhancer materialincorporated into the fiber, wherein the hydrophilic enhancer materialis selected from the group consisting of polybutylene, polybutylenecopolymers, ethylene/octene copolymers, and atactic polypropylene; and(d) a coating on the surface of the fiber containing an effective amountof an antimicrobial enhancer material; wherein the fiber isantimicrobial to Gram-positive bacteria and to Gram-negative bacteria,and wherein the antimicrobial enhancer material is selected from thegroup consisting of organic acids and chelating agents.
 10. The fiber ofclaim 9 wherein the antimicrobial enhancer material is lactic acid. 11.The fiber of claim 9 wherein the monoglyceride is a glycerolmonolaurate.